The present invention relates to an in-plane field type liquid crystal display device. More specifically, the invention relates to an in-plane field type liquid crystal display device having a structure which is prevented from being charged with electricity, and which is adapted to use of a black matrix having a high resistivity.
The conventional liquid crystal display devices can be divided into a "vertical field type" and an "in-plane field type" from the standpoint of the mode employed for driving the liquid crystals.
The vertical field type liquid crystal display device is one in which a pixel electrode and a common electrode made of transparent conductive material are provided facing each other in a unit pixel, and the light passing through the liquid crystal layer is modulated by an electric field generated across the pixel electrode and the common electrode perpendicularly to the transparent substrates.
On the other hand, the in-plane field type liquid crystal display device is the one in which at least a pair of electrode including a pixel electrode and a counter electrode are provided in a unit pixel on one or both of the transparent substrates, and the light passing through the liquid crystal layer is modulated by a field component generated between the pixel electrode and the counter electrode nearly in parallel with the surfaces of the liquid crystal layer.
Unlike the vertical field type liquid crystal display device, the in-plane field type liquid crystal display device enables the viewer to view a sharp image even when viewed at a large tilt angle, and thus features excellent wide viewing angle characteristics.
Liquid crystal display devices having such a constitution have been described in detail in, for example, Japanese Patent Application No. 505247/1993, Japanese Patent Publication No. 21907/1988 and Japanese Patent Laid-Open No. 160878/1994.
FIG. 7 illustrates a conventional liquid crystal display device in which a metal film, such as a film of chromium having an excellent light-shielding property, is used as a black matrix. The outer circumference of the black matrix BM is set to be sufficiently larger in a plan view than the effective pixel region AR and to be larger than the open region WD of the housing MD, making it possible to sufficiently intercept the backlight in the region where the black matrix is formed.
Therefore, the polarizer plates POL1 and POL2 can be designed to be smaller than the open region WD of the housing MD. This makes it possible to regenerate the polarizer plates, to prevent the polarizer plate POL2 from coming into contact with the housing MD in the step of assembling the module, and to prevent the polarizer plates from getting scratched.